3.2 million-year-old mystery: What killed Lucy?

Bones indicate she died from a long fall out of a tree, some scientists say

The discovery could yield clues to how our ancestors evolved from tree-dwelling apes.

BY CARL ZIMMERHEALTH + SCIENCE

In 1974, the paleoanthropologist Donald C. Johanson led an expedition to Ethiopia to look for fossils of ancient human relatives. Searching an expanse of arid badlands, he spotted an arm bone. In the area surrounding it, Dr. Johanson and his colleagues...